1. Field of the Invention
This invention relates to a method for doping solar grade silicon using an electric arc heater.
2. Description of the Prior Art
Heretofore, high purified silicon-tetrachloride (SiCl.sub.4) gas and a reducing agent, such as sodium or magnesium, were heated in the reaction zone of a high temperature electric arc heater by a high temperature gas such as mixtures of hydrogen and argon for silicon production. The metal reducing agent reacted with the silicon-tetrachloride to form molten silicon and a gaseous metal chloride. The silicon product was then separated from the gases in a cyclonic chamber with the silicon being removed from the bottom of the chamber for further processing while the gases were removed from the top of the chamber for recycling. One of the initial steps in silicon processing after removal from the collection chamber was to heat or remelt the silicon in a crucible under controlled atmospheric conditions, so that a doping agent, such as arsenic, could be added to the melt. The disadvantage of that process was that time was required for uniform dispersion of the dopant in the melt before further processing could begin. Moreover, extra energy was required to remelt the silicon.